Normally engaged spring clutch assembly drivable through either clutch drum

Abstract

The normally engaged spring clutch assembly has a helical spring in interference fit with driving and driven clutch drums to transmit rotation from one clutch drum to the other. A control sleeve surrounds and is in close spaced relation to the spring. Each of the opposite end portions of the spring are engageable with the sleeve so that, in the engaged condition of operation, the sleeve rotates with the spring and, in the disengaged condition of operation when rotation of the control sleeve is arrested, the spring is caused to release its grip on a clutch drum. The disengagement of the spring clutch assembly is achieved whichever clutch drum is the driving clutch drum. In another embodiment, the spring is so formed that, upon disengagement by arresting rotation of the control sleeve, a portion of the spring engages the control sleeve to stop the overrun of the driven clutch drum.

I claim: 
     
       1. A normally engaged spring clutch comprising: a. a first clutch drum having a peripheral clutching surface;   b. a second clutch drum having a peripheral clutching surface and spaced axially adjacent said first clutch drum;   c. a helical spring surrounding said first and second clutch drums and having, at least, some of coils thereof dimensioned to be in interference fit with the clutching surfaces of said first and second drums to transmit torque from one of said drums to the other;   d. a control sleeve surrounding said helical spring;   e. control means for selectively permitting and arresting rotation of said control sleeve; and   f. lost motion means interconnecting opposite end portions of the spring with the control sleeve so that, in engaged condition of operation, the control sleeve and spring rotate together and, in the disengaged condition of operation when rotation of the control sleeve is arrested, one end of the spring is held against rotation and caused to release its interference fit with a clutching surface of one of said first and second clutch drums.   
     
     
       2. The apparatus of claim 1 wherein said lost motion means comprises, at each end of the spring, a tang portion extending into an elongated opening in the control sleeve. 
     
     
       3. The apparatus of claim 1 wherein, in the torque transmitting condition of operation, a source of rotary power is connected to drive either the first and second clutch drums, and in a direction of rotation in relation to the winding of the spring, such as to increase the interference fit on the clutch drums driven by said source of rotary power. 
     
     
       4. The apparatus of claim 1 in which the spring has at least one set of coils, associated with a clutching surface of either said first or second clutch drums, of smaller size than the remaining coils. 
     
     
       5. The apparatus of claim 1 wherein the spring at opposite ends thereof and adjacent the clutching surface of said first clutch drum and adjacent the clutching surface of said second clutch drum have coils of smaller size than the coils therebetween. 
     
     
       6. The apparatus of claim 5 wherein the number of coils at each of the opposite ends of the spring does not exceed 3/8 of the total number of coils in the spring. 
     
     
       7. A normally engaged spring clutch comprising: a. a first clutch drum having an outer peripheral clutching surface;   b. a second clutch drum having an outer peripheral surface and disposed coaxially, end-to-end, with said first clutch drum;   c. a helical spring surrounding said first and second clutch drums and having, at least, some of its coils dimensioned to be in interference fit with the clutching surfaces of said first and second clutch drums to transmit torque from one of said first and second clutch drums to the other;   d. a control sleeve coaxially with and surrounding said helical spring;   e. control means for selectively permitting and arresting rotation of said control sleeve in either direction of rotation;   f. said spring having a radially extending first tang portion at one end of the spring and a radially extending second tang portion at the opposite end of the spring; and   g. a first elongated, arcuate opening in one end portion of the control sleeve and a second elongated, arcuate opening in the opposite end portion of the control sleeve to respectively receive therein, said first and second tang portions of the spring so that, in the engaged operative position, the first tang portion abuts a wall defining the first elongated opening in the control sleeve and thereby rotates the control sleeve with the spring and, in the disengaged operative position when the rotation of the control sleeve is arrested, the abutment of the first tang portion on said wall causes the coils adjacent said first tang to expand and release its interference fit on the clutching surface of the first clutch drum.   
     
     
       8. The apparatus of claim 7 wherein said spring has, at least, one coil of smaller internal diameter than the other coils so that the one coil has an interference fit with said clutching surface of said second clutch drum of greater magnitude than the other coils and thereby causes the adjacent second tang portion to be carried by the inertia of the second clutch drum, upon disengagement, into abutment with a wall of the second elongated opening in the control sleeve to stop such inertial rotation of the second clutch drum. 
     
     
       9. The apparatus of claim 7 wherein said spring has opposite end coil sections of smaller internal diameter than the coils therebetween so that the end coils more tightly grip the clutching surfaces of said first and second clutch drums than the intermediate coils. 
     
     
       10. The apparatus of claim 9 wherein the number of coils in each end coil section does not exceed more than 3/8 of the total number of coils in the spring.